Grey glass composition including erbium and holmium

Details Grey glass composition including erbium and holmium Grey glass composition including erbium and holmium

2001-06-27

2002-12-24

Sample, David (Department: 1755)

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

C501S070000, C501S071000

Reexamination Certificate

active

06498118

ABSTRACT:

This invention relates to glass compositions and methods of making the same.
More particularly, this invention relates to glass compositions including at least erbium (Er) and holmium (Ho), which have low light transmittance in the UV (ultraviolet) and IR (infrared) ranges and high light transmittance in the visible range. Such glass compositions are useful, for example, in windows and windshields in the automotive industry and also in architectural applications. Glasses herein may be grey, or otherwise colored.
BACKGROUND OF THE INVENTION
The automotive industry, for a number of years, has desired glass having grey color (sometimes called “neutral grey”) for automotive window applications. At the same time, it is also desirable for transmission in the UV and/or IR ranges of the light spectrum to be minimized. Moreover, certain Governmental regulations in the automotive industry have been known to require that visible light transmittance be at least 70% in certain vehicular windows when provided by the original equipment manufacturer of the vehicle (e.g. GM, Ford, Chrysler etc.) in the U.S.A. Accordingly, there exists a need in the automotive industry for a glass which achieves these properties (a similar need may also exist in other industries such as the architectural glass industry).
A glass window or other glass article is said to have the desirable color “grey” when it has a dominant wavelength of from 435 nm to 570 nm (this dominant wavelength range defines the color “grey” herein). Moreover, grey glass often has an excitation purity of less than about 4.5%. In certain embodiments, it may be preferable to have a dominant wavelength of from 470 nm to 570 nm, or even from 480-560 nm, with purity of from about 0.2 to 4.5%.
While glass having “grey” color is often desirable, there sometimes also exists a need or desire to achieve certain levels of light transmission defined conventionally by:
Lta as visible light transmission,
UV as ultraviolet light transmission, and
IR as infrared light transmission.
Glass thickness ranges of from about 1-6 mm, more preferably from about 3-mm, are typically used when measuring the aforesaid characteristics. These thickness ranges are generally recognized as conventional thicknesses for glass sheets made by the float glass process, as well as recognized thickness ranges in the automotive industry.
For automotive windows (including windshields) it is often desirable for glass to have one or more of the following characteristics at any or all of the aforesaid thicknesses:
Lta: at least about 70%
UV no greater than about 43%, more preferably no greater than 40%
IR: no greater than about 46%, more preferably no greater than about 42%
Classically formulated grey glasses often include low levels of iron (i.e., less than 0.2% total iron) along with cobalt and nickel oxides. Unfortunately, while this type of glass may achieve satisfactory coloration in certain instances, it typically suffers from undesirable solar characteristics. Certain nickel-free grey glasses combine selenium (Se) and cobalt (Co) oxide with iron oxide, but also suffer from poor solar performance characteristics.
Certain known green solar control float glasses are formulated so as to achieve desirable solar characteristics due in large part to their use of large quantities of total iron (e.g., 0.60 to 0.84% total iron). Unfortunately, the green coloration of such glasses does not always harmonize well with certain exterior automotive paints and sometimes affects vehicle interiors when viewed through the glass.
In view of the above, it is apparent that there exists a need in the art for a new glass composition which overcomes the above problems while achieving one or more of desired grey color and desired solar management property(ies) of the particular application in which it is to be used.
SUMMARY OF THE INVENTION
An object of this invention is to provide a grey glass (i.e., having a dominant wavelength of from 435 nm to 570 nm) including a colorant portion which may include at least from 0.20 to 2.50%, by weight, erbium oxide (e.g., Er
2
O
3
), from about 0.10 to 0.90%, by weight total iron (expressed as Fe
2
O
3
), and from about 0.10 to 1.60%, by weight, holmium oxide (e.g., Ho
2
O
3
). The combination of erbium oxide, iron oxide, and holmium oxide provides for desirable color and/or solar characteristics in different embodiments of this invention.
Generally speaking, certain example embodiments of this invention fulfill one or more of the above-listed need(s) or object(s) by providing a glass comprising a colorant portion including:
Ingredient
wt.%
total iron:
0.10-2.0% 
 
erbium oxide:
0.20-2.50%
holmium oxide:
 
0.10-1.60%.
In certain embodiments, the colorant portion may further include:
total iron:
0.10-0.90%
selenium:
 0.0-0.0020%
cobalt oxide:
 0.0-0.0050%
titanium oxide:
 0.0-2.0%
boron oxide:
 0.0-2.0%.
Certain other example embodiments fulfill one or more of the above listed needs and/or objects by providing a glass comprising:
the glass formed so as to have a dominant wavelength in the range of from 435 nm to 570 nm, and an excitation purity (Pe) of no greater than about 4.5%; and
wherein a colorant portion of the grey glass comprises iron oxide and at least three different lanthanide oxides, where a sum total of all of the lanthanide oxides in the glass is from 1.0 to 5.0%, by weight.
Still further example embodiments of this invention fulfill one or more of the above-listed object(s) and/or need(s) by providing a glass comprising:
a base glass portion comprising:
Ingredient
wt. %
SiO
2
67-75%
Na
2
O
10-20%
CaO
 5-15%
MgO
0-5%
Al
2
O
3
0-5%
K
2
O
0-5%
BaO
0-1%
and a colorant portion comprising (or consisting essentially of in other embodiments):
Ingredient
wt. %
total iron:
0.10-0.90%
erbium oxide:
0.20-2.50%
selenium:
  0.0-0.0020%
cobalt oxide:
  0.0-0.0050%
titanium oxide:
0.0-2.0%
boron oxide:
0.0-2.0%
holmium oxide:
0.10-1.60%
thulium oxide:
0.0-2.0%
ytterbium oxide:
0.0-3.0%
lutetium oxide:
 0.0-1.0%.
In certain embodiments, the glass may be grey in color and have an excitation purity (Pe) of no greater than about 4.5%, and a dominant wavelength in the range of from 435 nm to 570 nm.
In certain exemplary embodiments, the glass or glass composition is substantially free of cerium and/or nickel. In certain embodiments, the amount of Se may be from 0.0 to 0.0010%.
While grey color is preferred in certain embodiments, this invention is not so limited. Colorant portions herein may be used in conjunction with other glass colors in alternative embodiments of this invention.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THIS INVENTION
Glasses according to different embodiments of this invention may be used, for example, in the automotive industry (e.g., windshields, backlites, side windows, etc.), in architectural applications, and in other suitable applications. Such glasses may be grey, or otherwise colored in different embodiments of this invention.
Certain glasses according to this invention utilize soda-lime-silica flat glass as their base composition/glass, to which is added certain ingredients making up a unique colorant portion. An exemplary soda-lime-silica base glass according to certain embodiments of this invention, on a weight percentage basis, includes the following basic ingredients:
TABLE 1
Exemplary Base Glass
Ingredient
Wt. %
SiO
2
67-75%
Na
2
O
10-20%
CaO
 5-15%
MgO
0-5%
Al
2
O
3
0-5%
K
2
O
0-5%
BaO
0-1%
Other minor ingredients, including various conventional and refining aids, such as SO
3
, carbon, gypsum, CaSO
4
and the like may also be included in the base glass. In certain embodiments, for example, glass herein may be made from batch raw materials silica sand, soda ash (or NaOH as a soda source), dolomite, limestone, with the use of salt cake (SO
3
) and/or Epsom salts (e.g., about a 1:1 combination of both) as refining agents. Reducing agent(s) such as Si (metallic), Si, silicon monoxide, SiO, sucrose, and/or carbon may also be used. Preferably, soda-lime-silica

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